The present invention relates generally to training tools that improve throwing technique for sports that involve a thrown ball. Examples of such sports include baseball, softball, and cricket. More specifically, the present invention relates to those training tools that resemble a thick disk, biscuit or flattened ball, and provide immediate visual feedback upon being thrown.
A multitude of practice drills and devices have been developed in order to increase the command and accuracy of a thrown ball, the physics of which require precise throwing mechanics. As an example, in the sport of baseball, a baseball thrown by a pitcher observes many properties of classical mechanics found in translational motion or ballistic flight. Properties, such as the baseball's weight and rotation around its center of gravity, factor into the ball's flight path. That path, however, varies greatly from any theoretical ballistic flight calculation due to the baseball's raised stitching at its seams, which induce additional factors such as lift, drag, and Magnus forces that affect the ball's trajectory. Those forces, in turn, magnify the effects of the baseball's axis of rotation and angular speed, or spin, in determining the ball's trajectory, creating a variety of baseball pitches that exhibit varying curves and bends during flight. These pitches can broadly be identified as fastballs, curveballs, sinkers, and sliders, among others. For the aforementioned reasons, these baseball pitches, even those with the simplest throwing technique, can be difficult to master.
With the aim of refining the fundamental techniques for throwing a ball, several tools of the art exist, and as mentioned they resemble a thick disc, biscuit, or flattened ball. These tools generally exhibit a circular profile with two planar sides parallel to one another, and exhibit weights identical to those of a softball or baseball. These tools aim to provide visual feedback, indicating whether the tools were thrown with the proper technique, by not wobbling during its flight through the air. More specifically, the lack of wobble indicates that the tool's axis of rotation is stable and fixed in all three dimensions relative to a horizontal plane during the entire flight, thereby indicating a properly thrown tool. The technique used to properly throw such a tool is then transferred to the throwing of an actual ball. An example of such a training tool is disclosed in U.S. Pat. No. 5,472,187, entitled “Ball Pitch Training Device,” issued Dec. 5, 1995, the disclosure of which is incorporated by reference herein. An additional example is disclosed in U.S. Pat. No. 8,708,843, entitled “Ball Training System for Pitchers,” issued Apr. 29, 2014.
At present, training tools do not address a major factor that determines the flight path of a thrown ball. That factor is the ball's spin rate. For example, baseballs used in organized baseball leagues, such as Major League Baseball or the National Collegiate Athletic Association, are usually comprised of multiple layers. The spherical core of a baseball, known as a pill, is comprised of a high-density cork surrounded by two thin layers of rubber. This core has a diameter of roughly 10.47 mm. Wound around the pill is at least one layer of yarn. Thin layers of cotton, synthetic fabrics or elastomers may also be used in addition to the yarn. The ball is covered by two pieces of horsehide or cowhide tightly stitched together. The diameter of a baseball is 72.64 cm to 74.68 cm. As a result, a baseball has a core that is less dense than the outer layers of the ball. The lower density surrounding the pill creates a moment of inertia smaller than an identically shaped and identically weighted baseball that contains an evenly distributed density. For a given arm speed, this distribution of density within a baseball directly affects the angular speed around the ball's axis of rotation, which is a critical factor in baseball pitching. Therefore, a baseball's moment of inertia affects the technique of a thrower by forcing the thrower to consider and feel for the ball's moment of inertia in order to throw the ball with the thrower's intended trajectory.
At present, training tools that do not provide a substantially smooth surface where the fingers are placed can impede the successful training for many types of pitches. This is due to the fact that differences in finger placement that measure fractions of a millimeter in any direction can be the difference between a well thrown ball and a poorly thrown ball. Any raised surfaces located where the fingers grip the tool, other than those that mimic the stitching of an actual ball, reduced the effectiveness of the training tool.
At present, training tools exist that employ leather covers which scuff easily when the tools impact a hard surface. The resulting scuffs hinder the proper flight of the tool, rendering the tool less effective as a training aid.
In addition to pitching technique, a popular method for training pitchers in various sports employs balls that weight more or less than the regulation balls used during a game. This type of under- and over-weighted-ball training can increase the pitcher's arm conditioning and arm speed. At present, training tools weigh the same as the regulation balls they aim to mimic.